Crazy Diamond Performance (CDP) has expanded its development on Class 6 heavy duty engines to include a 7.4L supercharged CNG engine; the new engine will join the naturally aspirated 6.9L in the CDP Torquemaster family.

Both engines have been designed from the ground up for heavy-duty applications up to class 6. Under initial chassis testing, the Torquemaster 6.9L produced more than 375 hp (280 kW) and 500 lb-ft (678 N·m) of torque, with maximum torque generated by 2400 rpm. CDP expects the 7.4L low boost version to generate north of 650 lb-ft (881 N·m) of torque.

The engines are controlled by CDP’s GEM engine management harness/system, utilizing a current generation E-38 processor and is designed to be EMD+ and/or OBD compatible.

The 7.4L engine is a dual injector application, which is a bit different to what’s in the market currently, notes Kevin Fern, CDP president.

Internal engine components include a forged crankshaft and connecting rods. The pistons are also forged. The camshaft is a proprietary design, maximizing engine efficiency and performance in this low boost CNG application. The engine features a compression ratio of 10.2:1. The cylinder heads include lightweight stainless valves and hardened valve seats and are secured with 6 torque to spec bolts per cylinder. CDP will begin its testing of the new 7.4L engine in Q4 2014.

Ideal candidates for the Torquemaster engines are school buses and chassis/strip chassis applications, the company said.